U.S. patent number 5,295,872 [Application Number 07/908,397] was granted by the patent office on 1994-03-22 for biomedical electrical clasp.
Invention is credited to Eddy K. G. Christensson.
United States Patent |
5,295,872 |
Christensson |
March 22, 1994 |
Biomedical electrical clasp
Abstract
This invention provides a spring-operated biomedical electrical
clasp which includes a clasp base means and a clasp lever, each
having a handle end and a jaw end and each preferably being
composed of an insulating material such as plastic to provide
electrical shielding. The clasp lever is operatively associated
with the base member for articulation on the base member at a point
intermediate the ends of the lever. An electrically conductive
closing spring is connected to the clasp base member. The spring
has an intermediate upward projection, i.e., a deflection with
spaced upright legs that extends up from the base to the lever and
an upper closed end that functions somewhat in the nature of a
fulcrum for the lever but, through its resiliency, also yieldably
biases the jaw ends toward one another, i.e., to the closed
position. The spring can be a leaf spring. One portion of the
spring is a gripping portion positioned at the jaw end of the lever
to serve as an electrically conductive jaw face. Preferably, an end
portion of the closing spring adjacent the handle end of the base
(the end opposite from the jaw) includes a terminal portion with a
reverse bend having yieldable portions in opposition to one another
on each side of this bend to serve as a receptacle for frictionally
gripping a conductor, e.g., a pin connector which can be thrust
through an opening and between the opposing yieldable portions of
the spring.
Inventors: |
Christensson; Eddy K. G.
(Edina, MN) |
Family
ID: |
25425733 |
Appl.
No.: |
07/908,397 |
Filed: |
July 6, 1992 |
Current U.S.
Class: |
439/822;
439/909 |
Current CPC
Class: |
A61N
1/048 (20130101); H01R 4/4836 (20130101); H01R
11/24 (20130101); Y10S 439/909 (20130101); H01R
2201/12 (20130101) |
Current International
Class: |
A61N
1/04 (20060101); H01R 11/11 (20060101); H01R
11/24 (20060101); H01R 4/48 (20060101); H01R
004/48 () |
Field of
Search: |
;439/217,218,219,729,819,822,829,909 ;128/639,641 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Commercial Product: EKG Clip by Hirshman of America, Riverdale,
N.J. .
Commercial Product: "Astro-Trace" Clip by LeBlanc Corporation of
Augusta, Ga. .
Commercial Product: Trono MEd EKG Clip by Trono MEd, Inc. of
Irvine, Calif..
|
Primary Examiner: Schwartz; Larry I.
Assistant Examiner: Vu; Hien D.
Attorney, Agent or Firm: Harmon; James V.
Claims
What is claimed is:
1. A spring-operated biomedical electrical clasp for gripping a
biomedical skin-contacting electrode which is applied to the skin
of a patient, said clasp comprising:
a clasp base and a separate clasp lever each having a handle end
and a jaw end,
said clasp lever being operatively associated with the clasp base
for articulation relative to the clasp base intermediate the ends
of the lever,
an electrically conductive spring member having a portion connected
to the clasp base,
said spring member having a portion connected to the clasp
lever,
said spring member yieldably biasing the jaw end of the lever
toward a closed position with respect to the jaw end of the
base,
said spring member having a jaw face portion adjacent the jaw end
of said lever and said base to define an electrically conductive
jaw surface that is a portion of said spring, said spring biasing
the jaw surface toward an opposing jaw surface for releasably
gripping said biomedical electrode and for making electrical
contact therewith, and
the spring has a reverse bend at the handle end of the base, said
reverse bend includes an opening to provide an electrical coupling
receptacle for receiving and frictionally securing an electrically
conductive pin member to transfer electrical signals to or from the
clasp.
2. The clasp of claim 1 wherein the reverse bend has a yieldable
tongue yieldably biased to press against the pin member when the
pin member is inserted in the opening.
3. The clasp of claim 2 wherein the spring has a pair of said
yieldable tongues opposing one another adjacent the reverse bend to
frictionally hold the pin member and to establish electrical
contact therewith.
4. The clasp of claim 3 wherein one of the tongues has a
trough-shaped cross-section positioned in alignment with the axis
of the pin member when inserted into the clasp for making
electrical contact therewith.
5. A spring-operated biomedical electrical clasp for gripping a
biomedical skin-contacting electrode to be applied to the skin of a
patient, said clasp comprising:
a clasp base and a clasp lever each having a handle end and a jaw
end,
said clasp lever being operatively connected by means of a leaf
spring to the clasp base for articulation relative to the clasp
base,
said leaf spring is connected between the lever and the base for
supporting the lever on the base and for closing the clasp by
yieldably biasing the jaw ends of the base and lever toward one
another,
the leaf spring has a lower portion positioned proximate to the
clasp base and connected thereto,
said leaf spring has an intermediate section with a deflection
therein extending upwardly from the clasp base toward the lever,
and
the spring has a lever supporting portion connected to the lever
and located on the opposite side of the deflection from said lower
portion,
and the deflection has an upper portion positioned adjacent to the
lever that acts as a fulcrum for the lever when manual pressure is
applied to the lever for opening the clasp.
6. The clasp of claim 5 wherein the deflection has a pair of spaced
apart legs with an opening therebetween that can be used to receive
a metal snap element of a snap-style electrode.
7. The clasp of claim 5 wherein the base and lever are composed of
an insulating material to provide an electrical shield for the
clasp.
8. The clasp of claim 5 wherein the leaf spring includes a bend
adjacent the jaw end of the base, the intermediate section of said
spring extends from said bend toward the handle end of the base and
said spring has a reverse bend proximate the handle end of the base
with contact members on opposite sides of the bend and a pin
opening in the bend to receive a terminal pin to thereby serve as a
pin receptable for frictionally engaging said terminal pin.
9. The clasp of claim 5 wherein the leaf spring includes a pair of
opposing electrically conductive faces to receive a portion of said
skin-contacting electrode therebetween at the jaw end of the lever
and base, and said electrode is engaged by the opposing faces of
the same leaf spring to establish electrical contact with the
clasp.
10. The clasp of claim 5 wherein the spring has a receptacle
portion at the handle end of the base and the receptacle portion of
the spring includes an opening for receiving and contact means as a
part of the spring to frictionally secure an electrically
conductive pin member within the receptacle for transferring
electrical signals to or from the pin member to the clasp.
11. A spring-operated biomedical electrical clasp for a biomedical
electrode comprising:
first and second articulated clasp members, the clasp members each
having a jaw end and a handle end,
said clasp members being connected together by means of a leaf
closing spring, said spring yieldably biasing the jaw ends of the
clasp members toward one another, said second clasp member
comprises a base,
said leaf closing spring having end portions extending lengthwise
of each of the clasp members,
said spring also having an intermediate section with a bend
adjacent the jaw end of the clasp members,
a deflection in the intermediate section of the spring, said
deflection extending between the two clasp members and having a
portion raised above the base and positioned adjacent to the first
clasp member to act as a fulcrum for the first clasp member and to
help support the first clasp member as well as biasing the jaw end
of the first clasp member toward the jaw end of the base.
12. The clasp of claim 11 wherein the closing spring has a portion
that includes an electrical coupling receptacle with a contact
member as a part of the spring for receiving and securing an
electrically conductive pin member to the clasp.
13. The clasp of claim 12 wherein the receptacle has an opening to
receive the pin member and the receptacle has a tongue which
yieldably presses against the pin member when the pin member is
inserted into the opening in the clasp.
14. The clasp of claim 12 wherein the spring has an arcuate bend
therein and the contact member is a yieldable portion adjacent the
arcuate bend for frictionally holding the pin member in place and
to establish a good electrical connection with the pin.
15. The clasp of claim 11 wherein two opposing portions of the
spring define electrically conductive jaw faces at the jaw end of
the clasp members to establish an electrical circuit through the
spring with said electrode.
16. The clasp of claim 12 wherein a portion of the spring adjacent
the receptacle has a trough-shaped cross-section for guiding the
pin member when said pin member is inserted into the clasp.
17. The clasp of claim 11 wherein said leaf closing spring has
lower and upper adjacent opposing electrically conductive
cooperating jaw face portions located respectively at the jaw end
of the lower portion of the spring and a jaw end of the
intermediate section of the spring for gripping and establishing
electrical contact with the biomedical electrode.
18. The clasp of claim 17 wherein one of the jaw faces has a prong
extending therefrom for piercing said electrode.
19. The clasp of claim 11 wherein the spring is coated with an
electrically conductive substance and the lever and base are formed
from an electrically insulating plastic resin.
20. The spring-operated biomedical electrical clasp of claim 11
wherein one of the clasp members includes a stop member between the
jaw ends of the clasp members and the deflection in the spring for
limiting a distance that the biomedical electrode can enter the
clasp to prevent undesirable electrical contact with a matrix
portion of said biomedical electrode.
21. The spring-operated biomedical electrical clasp of claim 11
wherein the deflection is an archshaped portion of said spring
having a pair of upright legs extending from the base toward the
lever and the legs are joined together at their upper ends to
define the arch-shaped portion whereby a snap member provided on
said biomedical electrode can be introduced into the deflection
between said legs from one side of the clasp and the jaws then
allowed to close upon a head of said snap member.
22. A biomedical clasp for making contact with a biomedical
electrode, said clasp comprising,
a clasp base and a clasp lever, each including cooperating opposing
jaws at one end for gripping the biomedical electrode
therebetween,
a leaf spring connected between the clasp base and the clasp lever
for closing the jaws,
said spring having a flat section,
retaining means for securing the flat section of the spring in a
fixed position relative to the clasp base for forcing the jaws
together,
a deflection located between the opposing jaws and the retaining
means and said deflection is positioned to extend between the base
and the lever, said deflection having a free upper end adjacent the
lever to serve as a fulcrum for the lever,
said fulcrum allowing the jaws to be opened easily when finger
pressure is applied to the lever and engagement between the
retaining means and the spring providing a firm closing pressure
between the jaws of the clasp.
23. The clasp of claim 22 wherein the deflection is an arch-shaped
portion of said spring having a pair of upright legs extending from
the base toward the lever and being joined at their upper ends in
an arch, and said arch being adapted to support a lower surface of
said lever to serve as said fulcrum for said lever when finger
pressure is applied to a free end of said lever opposite the jaw
end thereof.
24. The clasp of claim 23 wherein a portion of the spring extends
from said deflection to a jaw end of said lever, said spring has a
bend therein adjacent the jaw end of said lever and said spring has
a lever supporting portion extending from said bend longitudinally
of said lever and when the clasp is closed said lever supporting
portion of said spring is inclined at an oblique angle with respect
to said base and is connected to said lever to support said
lever.
25. A spring-operated biomedical electrical clasp for gripping a
biomedical skin contacting electrode that is applied to the skin of
a patient, said clasp comprising:
an elongated clasp base having a handle end and a jaw end
portion,
a clasp lever connected to the clasp base and said clasp lever also
having a handle end and a jaw end, portion,
said clasp lever being operatively associated with the clasp base
for movement about a point of articulation relative to the clasp
base to permit the jaw end portions of the clasp base and clasp
lever to open and close for gripping the skin contacting
electrode,
a closing spring operatively associated between the clasp base and
the clasp lever for yieldably biasing the jaw end portions toward a
closed position for causing the jaw end portions to grip the
electrode,
an electrically conductive jaw face member connected to at least
one of said jaw end portions to define an electrically conductive
jaw surface positioned between the jaw end portions of the clasp
base and clasp lever,
electrically conductive means connected to the jaw face for
establishing electrical contact between the jaw face and a lead
wire that is to be electrically coupled to the clasp, and
at least one stop means as a part of the clasp between the jaw end
portions of the clasp base and clasp lever adjacent to the
electrically conductive jaw face for engaging and limiting a
distance that the biomedical skin contacting electrode can enter
the clasp to prevent undesired electrical contact between a matrix
portion of the biomedical electrode and the electrically conductive
jaw face,
said stop means is positioned upon one of said jaw end portions
between the electrically conductive jaw face and the point of
articulation of said clasp,
whereby the prevention of electrical contact between said matrix
and the clasp avoids impairment of electrical signals that would
otherwise result from such contact.
26. The spring-operated biomedical electrical clasp of claim 25
wherein the clasp includes a pair of laterally spaced apart stop
members positioned upon one of said jaw end portions adjacent to
the electrically conductive jaw surface and positioned between the
electrically conductive jaw face and said point of articulation and
said stop members extend from one of said jaw end portions toward
the other of said jaw end portions.
27. The clasp of claim 26 wherein the stop members are a part of
said clasp base and extend upwardly therefrom toward the clasp
lever.
Description
FIELD OF THE INVENTION
This invention relates to biomedical apparatus and more
particularly to a spring-operated clasp for connecting conductors
to biomedical electrodes that are placed in contact with the skin
of a patient.
BACKGROUND OF THE INVENTION
A biomedical electrode is a flexible, electrically conductive sheet
of material having a sticky surface which is placed in contact with
the skin of a patient for transferring electromedical signals, such
as cardiovascular signals, to electrocardiographic equipment or for
stimulating the patient by applying electrical current through the
electrode to the patient. Whether they are for stimulation or for
electrocardiographic readings, i.e., monitoring, the flexible
electrodes (referred to as external electrodes) are placed at
selected locations on the skin of the patient and are held in place
by adhesive. They include a conductive gel which provides the
required electrical conductivity for transferring signals to or
from the body through the electrode. These signals to or from the
body through the electrode. These electrodes include a lateral
extension (tab) on one side or a metal terminal, i.e., a steel snap
member to which a wire can be connected.
The present invention is concerned with the provision of an
improved connector or clasp for making electrical contact with such
monitoring or stimulating electrodes by securely gripping the tab
portion of the electrode or snap, as the case may be, as well as to
provide an electrical connection with several sizes of male
pin-type cable connectors that are now in common use for
transferring electromedical signals.
Clasps previously available have been complicated in construction,
subject to malfunction, and sometimes expensive to assemble. In
addition, they did not always provide a strong gripping force or,
in some cases, tended to be loose at the point of articulation so
that the jaws of the clasp could wobble from side to side. Another
problem was the requirement for using a threaded coupler or
soldered connection between the electrical lead wire and the clasp.
Another problem with many previously available clasps is that the
gripping portion, i.e., the jaw, has only one conductive surface,
causing an interruption in transfer of electrical signals when
accidentally attached upside-down to the electrode tab which is
only conductive on one side, usually its lower side.
A general objective of the invention is to provide an improved
clasp that is especially well suited for use with diagnostic
electrodes and is adapted to connect to both tab-type electrodes
and to snap-type electrodes.
A further object is to provide a clasp that can be easily opened
with moderate finger pressure but yet provides a strong, secure
closing action for reliably gripping the electrode.
Another object is to provide a clasp that is more reliable in
operation, less subject to damage or malfunction, and which can be
easily and quickly assembled.
A further object is to employ a single spring that supports a
gripping lever which closes the jaws and also provides a receptacle
at the other end for pin-type connectors of various sizes that are
now in commercial use. More specifically, it is an object to find a
way of using a spring which is of a one-piece, i.e. unitary,
construction that will eliminate the risk associated with a
soldered joint formerly used, which is subject to breakage, so as
to thereby guarantee an uninterrupted transfer of electrical
signals from the gripping jaws to the receptacle end of the clasp
to which is attached the pin connector at the end of a lead
wire.
It is another object to provide a spring that is wider wire springs
than presently used in the trade, so as to achieve a sturdier
construction and larger contact surface area for maximum
conductivity at the gripping end of the clasp.
Yet another object is to provide a simply constructed and reliable
clasp having an articulated clasp lever (for opening and closing
the jaws of the clasp) which is supported upon the base of the
clasp by a one-piece spring that provides the spring action for
closing the jaws of the clasp as well as for securing a pin
connector to the clasp.
Another object is to find a way of preventing the clasp from
accidentally contacting the sticky hydrogel portion of the flexible
electrode which, when it occurs, will cause what is known as
"base-line wander", a completely unacceptable condition that
distorts the electrical signal received.
Another object is to provide a retaining hook or prong which will
pierce the electrode tab yet cause less damage to the tab and, in
addition, is inherently easier to remove from the tab when the jaws
are open.
Yet another object is to find a way of preventing lead wires from
becoming entangled between the gripping end portions of the clasp
levers.
Still a further object is to provide resilient or yieldable
gripping elements that slidably engage and yieldably contact
opposing surfaces of a pin connector for securely gripping the pin
to provide a reliable electrical connection therewith.
These and other more detailed and specific objects of the present
invention will be apparent in view of the following description
setting forth by way of example but a few of the various forms of
the invention that will be apparent to those skilled in the art
once the principles described herein are understood.
SUMMARY OF THE INVENTION
This invention provides a spring-operated biomedical electrical
clasp which includes a clasp base means and a clasp lever, each
having a handle end and a jaw end and each preferably being
composed of an insulating material such as plastic to provide
electrical shielding. The clasp lever is operatively associated
with the base member for articulation on the base member at a point
intermediate the ends of the lever. An electrically conductive
closing spring is connected to the clasp base member. The spring
has an intermediate upward projection, i.e., a deflection with
spaced upright legs that extends up from the base to the lever and
an upper closed end that functions somewhat in the nature of a
fulcrum for the lever but, through its resiliency, also yieldably
biases the jaw ends toward one another, i.e., to the closed
position. The spring can be a leaf spring. One portion of the
spring is a gripping portion positioned at the jaw end of the lever
to serve as an electrically conductive jaw face. Preferably, an end
portion of the closing spring adjacent the handle end of the base
(the end opposite from the jaw) includes a terminal portion with a
reverse bend having yieldable portions in opposition to one another
on each side of this bend to serve as a receptacle for frictionally
gripping a conductor, e.g., a pin connector which can be thrust
through an opening and between the opposing yieldable portions of
the spring.
THE FIGURES
FIG. 1 is a bottom perspective view of the clasp of the present
invention;
FIG. 2 is a top perspective view of the clasp and in dotted lines a
pin connector of the type commonly connected to a lead wire to
which the clasp of the present invention is to be connected;
FIG. 3 is a side elevational view of the clasp with the jaws in the
open position and a flexible electrode tab between the jaws;
FIG. 4 is a side elevational view of the clasp with the jaws in the
closed position;
FIG. 5 is a top exploded perspective view of the clasp;
FIG. 6 is a bottom exploded perspective view of the clasp;
FIG. 7 is a plan view of the clasp base member on a larger than
FIGS. 1-6;
FIG. 8 is a side elevational view of the clasp base of FIG. 7;
FIG. 9 is a top view of the clasp lever on a larger scale than
illustrated in FIGS. 1-6;
FIG. 10 is a side elevational view of the clasp lever of FIG.
9;
FIG. 11 is a right end elevational view of the lever; and
FIG. 12 is a side view on a larger scale of the closing spring.
DETAILED DESCRIPTION OF THE INVENTION
Refer now to FIGS. 1-4, which illustrate an electrical connector or
clasp 10 in accordance with the present invention. The clasp 10
includes an elongated base member 12 (for convenience referred to
as a "base") and clasp lever 14 which articulates with respect to
the base 12 between an open position (FIG. 3) and a closed position
(FIG. 4). The base 12 and lever 14 can be formed from any of a
variety of materials such as metal or plastic, but are preferably
formed from an electrically insulating or shielding material such
as injection molded plastic, e.g., nylon which can be fiber
reinforced as with glass fibers, if desired. As seen best in FIGS.
5 and 6, a spring 16 which closes the clasp 10 as will be more
fully described below is a leaf type spring formed from a narrow
strip of flat-rolled, annealed steel, e.g., 1/4" wide and 0.015" to
0.018" inch thick. It can be plated, e.g., with coatings of copper
and nickel to enhance conductivity.
The base 12 will now be described with reference to FIGS. 5-8. As
seen in the figures, the base 12 is elongated, rectangular and has
a flat center portion 12a. It includes a pair of longitudinally
extending upright low side walls 12b and 12c which project from the
flat center section 12a. The side walls 12b and 12c terminate at
the left end of FIGS. 2-5 in a pair of upwardly extending fingers
or stops 12f and 12g which, as shown in FIG. 3, limit the distance
that tab 8 of skin-contacting electrode 11 can enter clasp 10. This
prevents electrical contact with the gummy matrix 9 which, if it
were to occur, would ruin the monitored electrical signals. The
right end of the base 12 as seen in the figures includes a collar
12d surrounding a longitudinally extending central opening 12e.
Projecting centrally from the side walls 12b and 12c are two
opposed centrally extending retaining studs 12h. The retaining
studs 12h help to hold the spring 16 in place during use. The studs
12h also provide firm pressure for keeping the jaw portions of the
clasp 10 closed as will be described more fully below. At the jaw
end of the base 12 is provided a round pocket 18 which accommodates
a prong P which projects from an upper face of spring 16. Other
retaining elements, such as studs 19, can be used to snap into
openings 160 in spring 16 to help hold it in place.
Refer now to FIGS. 5, 6, 9 and 10 with reference to the
construction of the clasp lever 14. As shown, the clasp lever 14 is
elongated, flattened and generally rectangular as seen in plan
view. It includes a handle end with an inner transverse rib 14a and
a jaw end 14b. The lever 14 has a pair of low, downwardly extending
side walls 14d and 14e and a tubular collar 14f (FIGS. 5, 6 and 10)
through which a portion 16d of spring 16 extends after assembly.
The collar 14f has a central flange 141 which, during assembly,
snaps into a like-shaped opening (FIGS. 5 and 6) in the deflection
16g of spring 16. A lug 14p also snaps into an opening in spring 16
to hold it in place.
During assembly, the upper free end of the spring 16 at 16a in FIG.
5 is thrust through the collar 14f to securely hold the lever 14 in
place on spring 16. It will be seen that in the resting position of
FIG. 4, the closing spring 16 will draw the jaw end 14b of the
lever 14 to a position proximate to the jaw end of the base 12, and
the handle end 14b of the lever 14 will be elevated where it can be
easily pressed down with a thumb or finger to open the jaws as
shown in FIG. 3.
The closing spring 16 will now be described in more detail with
reference to FIGS. 5, 6 and 11. As shown in the figures, the
closing spring 16 is a leaf type spring that has three main
sections, including two adjacent sections 16c' and 16c.sup.2 which
are joined by a reverse bend 16b at the right end of the clasp 10
as seen in the figures, and an upper inclined section 16d
terminating in the free end 16a. The bend 16b preferably is a
circular arc with a central opening 16e to receive a pin connector
7 (FIG. 2). The reverse bend 16b in this way serves as a pin
receptacle for an electrode pin 7 (FIG. 2). On opposite sides of
the bend 16b are opposing resilient and yieldable tongue-shaped
contact members 16f, 16f' enable the receptacle to frictionally
grip the pin connector 7 when inserted through the opening 16e.
During assembly, the reverse bend 16b is inserted into the opening
12e of the collar 12d of the base 12. The yieldable portions 16f
and 16f' provide a smooth sliding contact with the electrical
terminal pin 7 (FIG. 2) when it is slid into the opening 16e to
provide electrical contact therewith. The lower contact members
16f' can have a trough-shaped cross-section to conform to the pin 7
for guiding the pin and for making electrical contact with the pin
as it passes through the opening 16e into the clasp 10. The
opposing contact members 16f and 16f' press down on the pin 7 due
to their own resiliency and the resiliency of the reverse bend 16b
of the spring 16 to hold the pin 7 securely in place and establish
good electrical contact.
The base portion at 16c.sup.2 has a free end at the left end of the
clasp 10 which serves as an electrical contact surface for the
lower jaw. The intermediate section 16c' of the spring 16 is
provided with an upwardly projecting deflection 16g having
longitudinally spaced upright legs 16h and 16i that extend from the
base 12 toward the lever 14. As shown in FIG. 12, the upper end of
legs 16h and 16i join one another at an arch-shaped free upper end
portion designated 16j. The arch-shaped free upper end portion 16j
of the deflection 16g which is located adjacent to the lever 14
(FIG. 4) functions somewhat in the nature of a fulcrum for the
lever 14. However, through its resiliency it also biases the jaws
toward one another, i.e., to the closed position. As seen in FIG.
12, a horizontal portion 16j' of spring 16 extends from the
deflection 16g to the jaw end 14b of lever 14. The spring 16 has a
bend 16k therein adjacent to the jaw end 14b of lever 14 and the
spring has a lever supporting portion 16d extending from the bend
16k longitudinally of lever 14 that is inclined at an oblique angle
with respect to the base 12. The lever supporting portion 16d is
connected to the lever 14 for supporting it. It will be seen in
FIG. 12 that before finger pressure is applied, i.e., when the
spring 16 is in a relaxed condition, to horizontal portion 16j' to
the left of the deflection 16g contacts the left end of the bottom
portion 16c.sup.2. In this way, portion 16j' and the adjacent end
of portion 16c form jaw faces which securely grip the tab 8 of the
skin-contacting electrode 11 (FIG. 3) to provide a reliable
electrical and mechanical connection with the electrode 11. The
contact surfaces of the jaw faces can be serrated, if desired, to
provide more surface friction and to provide a more secure grip on
the tab 8 of the electrode 11. In this case, at the center of
portion 16j' is a pointed prong P or hook which is bent downwardly
to project through a central opening in the jaw face near the left
end of portion 16c to pierce and hold the tab 8 securely but yet
release it reliably when the jaws are opened because the tab 8
tends to fall away from the prong P. In addition, the prong P,
because it is on top, has little tendency to damage the metal
coating on the bottom of tab 8.
Assembly of the clasp 10 is easily accomplished by sliding the pin
receptacle portion within the reverse bend 16b of the spring 16
into the collar 12d. As this is done, both sections 16c' and
16c.sup.2 slide under the opposed retaining studs 12h. The lever 14
is then slid into place on the upper jaw portion 16a of the spring
16 and forced toward the right as seen in FIGS. 2-4 until the bend
16k slides through the slot 14f in the lever 14. The upper portion
16a of the spring 16 will also come to rest between the side walls
14d and 14e, with its free end adjacent the inner surface of the
transverse rib 14a. The clasp 10 is then ready for use. Since all
electrical connections are made through adjacent metal jaw surfaces
of spring 16 and via the receptacle within the reverse bend 16b at
the opposite end of the spring 16, a reliable electrical connection
is achieved through a single working part, namely, the spring 16.
This makes the clasp 10 more reliable because it eliminates the
possibility of an open circuit.
It will be noticed that the deflection 16g acts somewhat as a
fulcrum by permitting articulation of the lever 14. It also
supports the lever 14. The deflection 16g thus functions to replace
hinges formerly used in biomedical electrical clasps. Since a true
hinge is not needed, the closing action is smooth and there is
little opportunity for parts to wobble. In addition, electrical
continuity is assured and assembly is simplified, thereby reducing
production costs.
One preferred method of forming the spring 16 will now be
described. The spring 16 is about 0.25 inch wide and about 4.4
inches long. It can be formed from a strip of 1095 annealed steel
(flat on roll) and is then bent to the shape shown. Low carbon,
flat-rolled steel having a nominal thickness of about 0.015 inch to
0.018 inch can be employed. The springs are then heat-treated at a
temperature that will produce a Rockwell hardness level of from 47
to 52. The spring is next deburred, preferably by tumbling the
spring in a vat filled with an abrasive liquid for a period of
about 30 minutes to 45 minutes. Approximately 2,500 springs are put
in a drum at one time. This smooths out the rough places in the
spring steel and allows for better plating. A copper flash is then
plated on all surfaces to a thickness of 0.00005 inch. Next, an
electroless nickel plating is applied to a thickness of
0.0001-0.0002 inch. The parts are then baked within one hour of
plating for eight hours at 350.degree. F. to 375.degree. F. The
lever 14 can have a length of about 1.15 inches and a width of
about 0.32 inch. The base 12 can have a length of about 1.56 inches
and a width of about 0.32 to about 0.41 inch, with other parts of
proportionate size.
The present invention provides a clasp structure having a
receptacle with the reverse bend 16b adapted to accommodate a
variety of different pin sizes. For example, manufacturers commonly
employ terminal pins having diameters of, say, 2 mm, 3 mm and 4 mm.
All of these sizes can be accommodated by the receptacle of the
present invention. The clasp 10 does not require a soldered
connection between the pin 7 and clasp 10, nor a threaded
connection which adds cost and takes time to assemble.
Consequently, the receptacle can be considered universal with
respect to its ability to accommodate pin terminals of various
sizes.
It can also be seen that the base 12 and the lever 14 provide
electrical insulation and shielding. In this way, they reduce the
opportunity for the clasp 10 make electrical contact with any other
conductors that may be in the vicinity of the patient to prevent
extraneous signals from entering the system or from interferring
with the signals being transferred. In addition, they help prevent
electrical shocks in the event the electrode is used for heart
stimulation, and the stops 12f and 12g prevent accidental
electrical contact between the jaws and the gummy matrix 9 of skin
electrode 11. As can be seen in FIG. 4, the side walls 14d and 14e
prevent lead wires from becoming caught and entangled between the
base 12 and the lever 14.
Another important advantage of the invention is that the deflection
16g provides an opening for the metal snap of a snap-style
electrode. Consequently, the invention can be used with all skin
electrodes, whether they are the tab-type electrode as shown in
FIG. 3 or the snap-type electrode which has a metal snap member
that extends from the upper surface of the electrode. To make
contact with a snap, the clasp 10 is turned on its side and the
snap (not shown) is introduced into the deflection 16g from the
side of the clasp 10, i.e., between the legs 16i and 16h. The jaws
are then allowed to close upon the head of the snap element. When
the clasp 10 is closed, portions of the base 12 just beneath the
deflection 16g force the steel snap element into electrical contact
with the underside of deflection 16g to hold the snap in place.
A surprising benefit of the invention is that, in spite of the firm
closing pressure of the jaws made possible by the downward force of
the retaining studs 12h on spring 16, the jaws are nevertheless
quite easy to open because of the fulcrum effect provided by the
deflection 16g. This allows the jaws to be opened easily by
applying pressure with the index finger and thumb, yet the jaws
hold the tab 8 with a firm grip.
Many variations of the present invention within the scope of the
appended claims will be apparent to those skilled in the art once
the principles described herein are understood.
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